1. Field of the Invention
The present invention relates to a connector to be connected to flexible, planar cables such as FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable). Hereinafter in this specification, a flexible, planar cable will be generically referred to as a FPC. Furthermore, the present invention relates to a connector for FPC of ZIF (Zero Insertion Force) type, that hardly needs any force for insertion and removal of the FPC.
2. Description of Related Art
In recent years, a connection between electronics modules or print substrates implemented in electronic equipment such as DVC (Digital Video Camera) and DSC (Digital Still Camera) or mobile information equipment represented by mobile phone and PDA (Personal Digital Assistance), a FPC, a flexible and planar cable, has been adopted.
A connector for FPC to be implemented on the surface of a printed circuit board, i.e., a surface mounted connector for FPC, comprises an insulative housing having an insertion portion formed for the insertion of FPC, and a plurality of contacts attached side by side in a predetermined pitch to the housing. In order for contacting the FPC with these contacts, a covering housing that can open and close is provided in the insertion portion.
The connector for FPC to be mounted on the surface of a printed circuit board, in order to attain a higher density, is required to have a lower height (a reduction in profile). The contacts that are aligned in the surface mounted type connector for FPC are increasingly made with more pins in a finer pitch therebetween.
As such surface mounted type connector for FPC, a connector has been invented (see, for example, Japanese Patent Application Laid-Open No. 2002-329536) wherein a plurality of contacts that comprises a contact leg contacting the FPC, and a stabilizer leg corresponding to the contact leg is configured in a first contact group and a second contact group that align in parallel with each other.
The connector for FPC according to Japanese Patent Application Laid-Open No. 2002-329536 is provided with a cam that engages the stabilizer leg in the first contact group at an actuator (hereinafter referred to as a cover housing) that opens and closes, and a pressed portion that engages the stabilizer leg in the second contact group.
The cam that is formed around a pivot shaft of the cover housing is elastically deformed such that the stabilizer leg in the first contact group widens the interval between the corresponding contact legs when the pivot shaft rotates to move the cover housing from the closed position to the opening position.
On the other hand, the pressed portion is formed in such a way that the stabilizer leg in the second contact group receives a force that is in an opposing direction of the force given by the stabilizer leg in the first contact group to the cover housing when the pivot shaft rotates to move the cover housing from the closed position to the opened position.
When the cover housing is rotated to open the insertion portion of the FPC, the connector for FPC according to Japanese Patent Application Laid-Open No. 2002-329536, elastically deforms the stabilizer leg of the first contact group and widens an interval between the contact leg and the pressing portion of the FPC provided in the stabilizer leg. The literature also describes that the deformation of the cover housing can thus be prevented or controlled without damaging the ZIF action.
In addition, Japanese Patent Application Laid-Open No. 2002-329536 describes about the connector for FPC that the first contact group and the second contact group will not give the cover housing any force that causes adverse deformation under a state where the cover housing is closed.
As such surface mounted type connector for FPC, a connector has been invented (see, for example, Japanese Patent Application Laid-Open No. 2003-151660) that comprises an insulative housing, a plurality of contacts installed in the housing, and the cover housing rotatably provided thereto.
The contact of the connector for FPC according to Japanese Patent Application Laid-Open No. 2003-151660 comprises a contact beam extending toward the insertion portion of the FPC and a pivot beam. The lower edge of the tip side of the pivot beam is formed with a notch to construct the pivot portion of the cover housing.
Furthermore, in the connector for FPC according to Japanese Patent Application Laid-Open No. 2003-151660, a through hole is formed corresponding to the pivot portion of each contact in the cover housing. The circumference of the through hole is described as an axial portion of which cross-section is approximately circular and engages the pivot portion. A protrusion for pressurization is provided between the adjacent axial portions to press the FPC toward a direction of the contact point of the contact.
In such configuration of the connector for FPC according to Japanese Patent Application Laid-Open No. 2003-151660, the cover housing is easily assembled to the housing, and at the same time, will not damage the contact point of the contact during assembly.
FIG. 14 is a sectional view of a connector 7 for FPC according to Japanese Patent Application Laid-Open No. 2002-329536. FIG. 14 in the present invention corresponds to FIG. 3 in Japanese Patent Application Laid-Open No. 2002-329536. In FIG. 14, a housing 70 includes an insertion portion 70A in which FPC 1 is inserted. A first contact leg 71A in the first contact 71 is pressed from the insertion portion 70A side into the housing 70. One end of the first contact leg 71A forms a lead portion extending from the housing 70 and solder jointed to a printed circuit board 9.
As shown in FIG. 14, the other end of the first contact leg 71A is inverted and branched in U-shape to form a first stabilizer leg 71B that extends to a side of insertion portion 70A. The tip of the first stabilizer leg 71B then engages a cam 73A that is formed in the circumference of the pivot shaft of the cover housing 73.
FIG. 15 is a sectional view of a connector 7 for FPC according to Japanese Patent Application Laid-Open No. 2002-329536. FIG. 15 in the present invention corresponds to FIG. 4 in Japanese Patent Application Laid-Open No. 2002-329536. In FIG. 15, the second contact 72 have a second contact leg 72A and a second stabilizer leg 72B disposed opposingly with each other, one end of the second contact leg 72A and one end of the second stabilizer leg 72B are connected to form a bifurcated contact.
As shown in FIG. 15, the second stabilizer leg 72B is pressed from an opposing side of the insertion portion 70A into the housing 70. The other end of the second stabilizer leg 72B is a free end that extends from the housing 70. The free end engages a pressed portion 73B that is formed in the circumference of the pivot shaft of the cover housing 73. One end of the second contact leg 72A extends from the housing 70 to form a lead portion that is solder jointed to a printed circuit board 9 (refer to FIG. 14)
The contacts aligned in the surface mounted type connector for FPC are increasingly made with more pins in a finer pitch therebetween. Accordingly, the contacts 71 and 72 shown in FIGS. 14 and 15 are plate springs that are thin in plate thickness. In addition, the contacts aligned in the surface mounted type connector for FPC are reducing its height and having finer pitch therebetween. To cope with this development, a wall C between polar (in a shape of the teeth of comb) of the housing 70 that holds a fixed end of the second stabilizer leg 72B shown in FIG. 15, for example, is made thinner.
In FIG. 14, when the cover housing 73 is opened, a cam 73A formed in the circumference of the pivot shaft of the cover housing 73 to act as a eccentric cam rotates to dispose the end of the first stabilizer leg 71 B in an upper position. In brief, as shown in FIG. 14, upon rotation of cam 73A in the pivot shaft of the cover housing 73, an upward force R acts.
On the other hand, as shown in FIG. 14, an opposing force S acts when the first stabilizer leg 71 B tries to have its end portion return to its position. Accordingly, as shown in FIG. 15, when the opposing force S acts, the pressed portion 73 B that is to be integrated with the pivot shaft of the cover housing 73 energizes a tip of the second stabilizer leg 72 B into a downward direction.
Upon opening the cover housing 73, the second stabilizer leg 72 B generates a bending moment in a counter clockwise direction with a lead portion (a lead portion to be an end of the second contact leg 72A) solder jointed to the printed circuit board 9 (refer to FIG. 14) as a supporting point.
As described above, because the wall C between electrodes of the housing that holds a fixed end of the second stabilizer 72B is thin, a stress acts upon a thin wall C between electrodes that have the second contact 72 pressed therein, therefore tending to cause a breakage problem.
Further reduction of the profile in the surface mounted connector for FPC results smaller sectional area of the cam 73B that is to form an eccentric cam. Additionally, as a contact provided with more pins is increasingly sought, it causes a longer pivot shaft that connects cam 73A in an axial direction.
It is feared that, in a process of opening the cover housing 73, such a long length of pivot shaft will be deformed at the center portion due to the opposing forces S on a number of the first stabilizer legs 71 B. Specifically, it is feared that the pivot shaft will have the center portion deformed by way of action of equally distributed load across the end of support beam. It is conceivable that the deformed center portion of the pivot shaft may cause difficulty in opening the cover housing 73.
It is desirable that a ZIF type connector for FPC has more pins in finer pitch with a reduced profile, and also is configured to ensure the opening and closing operation of the cover housing.
FIG. 16 is a sectional view of a connector for FPC 8 according to Japanese Patent Application Laid-Open No. 2003–151660. The FIG. 16 of the present invention corresponds to FIG. 3 in Japanese Patent Application Laid-Open No. 2003-151660. In FIG. 16, the housing 80 have the insertion portion 80A in which the FPC 1 is inserted. Contact beam 81A and pivot beam 81B forming a terminal (hereinafter, referred to as a contact) 81 are pressed into the housing 80 from the opposing side of the insertion portion 80A. An end portion of the contact beam 81A forms a lead portion extending from the housing 80 and solder jointed to the printed circuit board (not shown).
FIG. 16 is a state diagram showing a cover housing 83 in an opened position. As shown in FIG. 16, a notch 811 is formed at a lower edge of the tip of the pivot beam 81B. A pivot portion 812 that rotatably supports a shaft 83A of the pivot shaft of the cover housing 83 forms a notch 811. A through hole 831 is provided around the shaft 83A.
FIG. 17 is a sectional view of a connector for FPC 8 according to Japanese Patent Application Laid-Open No. 2003–151660. The FIG. 17 of the present invention corresponds to FIG. 4 in Japanese Patent Application Laid-Open No. 2003-151660. FIG. 17 is a state diagram showing a cover housing 83 in a closed position. As shown in FIG. 17, a pressure protrusion 832 formed at a bottom wall of the cover housing 83 presses FPC1.
In the connector 8 according to Japanese Patent Application Laid-Open No. 2003-151660, the opening size A of the through hole 831 to be formed in the cover housing 83 is made smaller than the size B in a height direction of the pivot portion 812 of the contact 81 in a way that the cover housing 83 will not come off from the pivot portion 812 of the contact housing 83 during opening and closing of the cover housing 83. As a result, the connector for FPC will be achieved with reliable connecting operation of the FPC
The contact that is aligned in the surface mounted type connector for FPC are increasingly made with more pins in a finer pitch therebetween. Accordingly, the contact 81 in FIGS. 16 and 17 are plate springs that are thin in plate thickness. In addition, the surface mounted type connector for FPC is reducing its height. The thickness of the housing 80 that holds a fixed end of the pivot beam 81B shown in FIG. 16, for example, is made thinner.
In the connector 8 shown in FIGS. 16 and 17, a plurality of contacts 81 is aligned in a line in the housing 80. In a state where the FPC 1 is inserted into the connector 8 and the cover housing 83 is closed, as a result of the contact beam 81A, a bending moment in a counter clock direction acts upon the pivot beam 81B of a cantilever beam.
The pivot beam 81B of a cantilever beam as in a shape shown in FIGS. 16 and 17, however, when the thickness of the plate is made thinner and the profile is reduced, cannot be a rigid arm having large geometrical moment of inertia that can counteract the aforementioned bending moment.
Stated differently, it cannot counter the concern that the pivot beam 81B of a cantilever beam undergoes uniformly distributed load of deflection in an upper direction. This may cause a problem of, for example, a contact failure between the FPC and the contact.
In a connector for FPC having contacts that has more pins in a finer pitch therebetween and with a low profile, it is desirable that the connector for FPC is configured to have a cover housing that can maintain reliable opening and closing position to avoid contact failure.
In view of these problems, it is an object of the present invention to provide a connector for FPC having contact that has more pins in a finer pitch therebetween and with a low profile, and that is configured to ensure the opening and closing operation of the cover housing, and at the same time, to maintain its opening and closing position.